This invention relates generally to hydraulic fuel systems for internal combustion engines. More particularly, this invention relates to hydraulic fuel systems for diesel engines with hydraulically activated electronically controlled unit injection.
Many diesel engines use hydraulically activated electronically controlled unit injection (HEUI) fuel systems to improve engine performance. HEUI fuel systems, also referred to as hydraulic fuel systems, require high-pressure oil to operate the fuel injectors. In particular, the HEUI system employs high pressure lube oil acting on an intensifier piston in the top of each fuel injector to drive down a fuel plunger and thereby eject fuel. Existing HEUI fuel systems, typically have a high pressure lube oil circuit and a low pressure oil circuit and a high pressure oil pump cooperatively between them.
Existing HEUI fuel systems typically have various components mounted externally to the engine, and in particular to the engine crank case. The high pressure oil circuit, for example, has an externally mounted high pressure pump and externally routed high pressure oil lines that deliver high pressure oil to high pressure rails or reservoirs. Also, the low pressure oil circuit typically has a low pressure oil cooler that is also mounted externally to the engine crankcase. Further, the low pressure oil cooler and a low pressure oil reservoir, which feeds low pressure oil to the high pressure pump, are typically separate components in existing hydraulic fuel systems. The location, relative to the engine, of these various components results in a large number of components needed to provide the high pressure oil in existing HEUI fuel system. Moreover, the externally mounted nature of these components typically increases the size of the engine compartment space required by engines using the HEUI fuel system.
In addition, the externally mounted and separate component have a greater probability of developing oil leaks and adversely impacting the engine performance and the environment outside the engine. The externally mounted and separate hydraulic fuel system components also tend to lead to higher engine manufacturing time, costs and complexity due to a greater number of components being mounted to the engine.
Accordingly, there is a need for a hydraulic fuel system, which provides high pressure oil, with reduced space requirements while minimizing the impact of oil leaks in the hydraulic fuel system oil circuit.
The present invention provides a hydraulic fuel system, or hydraulically-operated electronically controlled fuel injector system, having an integrated and internally mounted oil circuit for providing appropriate high pressure required in the HEUI fuel system. There is provided an internally mounted high pressure pump connected to internally routed high pressure lines or tubes that deliver oil from the high pressure pump to high pressure oil reservoirs or rails. The high pressure pump is internally mounted in a high pressure pump housing in the crankcase and the high pressure oil lines are internal to the engine. The high pressure pump housing is positioned in a rear top portion of the crank case in the V-portion of a V-type engine. The high pressure oil lines comprise flexible tube sections and other components to reduce vibrational wear. There is also provide an integrated low pressure oil reservoir which is positioned in a front top portion of the crank case in the V-portion of the engine. The integrated low pressure oil reservoir comprises a low pressure oil cooler and a low pressure oil. The oil cooler or heat exchanger is immersed inside the low pressure oil reservoir to reduce space and improve heat transfer. The integrated low pressure reservoir also has a high pressure pump filter that covers a high pressure pump feed passage that supplies low pressure oil to the high pressure oil pump. The filter prevents debris from passing into the high pressure oil pump and other components on the high pressure oil circuit of the hydraulic fuel system.
The hydraulically-operated electronically controlled fuel injector (HEUI) system
for an internal combustion engine for actuating a fuel injector comprises a controller able to receive an actuating fluid pressure measurement from an ICP sensor; an IPR valve; at least one high pressure actuating fluid reservoir; an integrated low pressure fluid reservoir; a rear gear driven high pressure pump disposed in a high pressure pump housing and operatively connected to the integrated low pressure fluid reservoir; and an internally disposed high pressure fluid line operatively connecting the high pressure pump and the at least one high pressure actuating fluid reservoir, whereby the controller selectively modifies pressure in the high pressure fluid line via selective actuation of the IPR valve to obtain a desired pressure in the at least one high pressure actuating fluid reservoir.
Additionally, the high pressure pump housing further comprises a high pressure pump cover and a high pressure pump mounting in a rear top crank case area. And, the high pressure pump housing and the integrated low pressure fluid reservoir are disposed between a first and a second cylinder head. The HEUI system also has an integrated low pressure fluid reservoir comprising a low pressure fluid cooler and a low pressure fluid housing in a front top crank case area, a high pressure pump filter and a high pressure pump feed passage connected to the high pressure pump.
The high pressure fluid line further comprises a high pressure discharge tube attached to the high pressure pump; a branch tube section attached to the high pressure discharge tube; a rigid tube section attached to the branch tube section; a flexible tube section attached to the rigid tube section; and a high pressure check valve attached between the flexible tube section and the high pressure actuating fluid reservoir.
The following drawings and description set forth additional advantages and benefits of the invention. More advantages and benefits will be obvious from the description and may be learned by practice of the invention.